"Generics" are a type of constructor syntax in Java which doesn't seem to play well with however Domino implements Java compiling. Try compiling outside of Domino Designer and importing the Jar to use it. That should get you around the problem.
You can read more about Generics here: http://java.sun.com/docs/books/tutorial/java/generics/gentypes.html
It's basically a cryptic shorthand method for reducing the amount of code you have to write to get a bit more flexibility out of your compiled library.